They set an ambitious goal: Increase the average speed on the state's most gridlocked freeway by 15 percent.

Engineers believe they have found a way to help motorists avert time-consuming and nerve-jarring traffic jams while cutting fuel consumption and air pollution from the 3.5 million vehicles that crowd 27 freeways each day.

When an accident occurs, traffic engineers using video cameras pinpoint the location and dispatch help. Meanwhile, message signs on the freeway alert motorists to use surface streets to get around the crash site, and people getting off work can log onto an Internet site or call a hot-line that warns them to use alternate routes.

If this so-called "smart corridor" system being tested on the Santa Monica Freeway proves successful, it eventually could serve as a blueprint for traffic engineers across the nation.

"We don't have the space or the money to build new freeways, so in lieu of that we have to make existing freeways more efficient," said Larry Zarian, chairman of the Los Angeles County Metropolitan Transportation Authority, one of several agencies sponsoring the project. "If the experiment tells us this is cost-effective, we will see this in other places."

Between 1980 and 1990, commuting time in most major U.S. cities rose by nearly one minute on average, according to the Eno Transportation Foundation, a think tank based in Lansdowne, Va. In Los Angeles, commuting time rose more than 12 percent, an average of three minutes.

After decades of watching freeways gobble up large swatches of land, little popular support exists for new ones.

Many states--including New York, Texas and Washington--have introduced technology aimed at improving highway speed on a limited basis. In the Chicago area, a plan is in the works to use a variety of devices, including in-vehicle navigation equipment, that by the turn of the century would help whisk motorists around traffic snarls from Milwaukee to Gary.

Results, according to experts, are mixed.

"Right now, the (improvements in travel speeds) are small and incremental," said Jennifer Clinger, a policy analyst at the Eno Transportation Foundation.

The $48 million Santa Monica Freeway project was financed by several agencies, including Caltrans (California's transportation department), the U.S. Highway Administration and Los Angeles Department of Transportation.

The experiment encompasses a 17-mile stretch of the five-lane Santa Monica Freeway, where vehicles crawl along at 20 to 25 miles per hour during rush hour. With 340,000 vehicles per day, it is one of the nation's busiest freeways.

Besides having the capability of communicating with motorists, the system is linked with 540 traffic signals on numerous arterial roads adjacent to the freeway. When a traffic jam occurs, engineers at a command post can use the message signs to divert traffic onto surface streets and can accommodate the overflow by re-timing the traffic lights for longer greens.

"The beauty of this is the sharing of information between the agency that oversees the freeway and the agency that oversees the traffic lights," said Jeff Lindley, deputy director of integrated transportation at the Highway Administration.

Still, in an area where one all-news radio station broadcasts traffic reports every six minutes, even those efforts aren't enough.

Traffic engineers, in unrelated projects, have opened an elevated car-pool lane on a downtown Los Angeles freeway and a fully-automated tollway in Orange County.

And one futuristic-sounding plan would allow drivers to kick back--read a book, take a snooze or work on a computer laptop--as their vehicles automatically whiz them to their destinations.

A consortium of university professors, state and federal traffic experts and automotive engineers is developing an "automated highway" in San Diego, a system that will rely on magnets embedded in the highway and radar devices installed on vehicles.

The idea is to reduce the distance between vehicles and boost the speed by removing a key source of traffic problems: The driver, particularly the type prone to cause accidents by cutting across several lanes without signaling.

That plan, though, is not expected to fully materialize for at least 15 years.